Impact of residual mitral regurgitation after transcatheter edge-to-edge repair in atrial functional mitral regurgitation: Results from MITRA-PRO registry

Background: Transcatheter edge-to-edge repair (TEER) has emerged to address symptomatic atrial functional mitral regurgitation (aFMR) in patients who are at high operative risk. Aims: No clinical data is available on the impact of residual mitral regurgitation (MR) following TEER in aFMR compared to ventricular functional MR (vFMR). Methods: In the MITRA-PRO registry, 846 patients with FMR and MitraScore assessment for residual MR quantification were included (722 patients with vFMR and 124 patients with aFMR). Results: Compared to vFMR similar procedural results in regard of residual MR following TEER were found in aFMR patients (MitraScore post TEER 2.5 ± 1.8 vs. 2.7 ± 1.9), while the amount of implanted TEER devices was increased in vFMR. 1-year survival was better in aFMR compared to vFMR regardless of relevant residual MR (MitraScore ≥ 4), while 1-year rehospitalization was comparable for both MR entities. Patients with aFMR and mild residual MR had a lower mortality rate (6.6% vs. 10.3%) and rehospitalization rate (29.1% vs. 46.2%) 1 year after mitral TEER. However, in contrast to vFMR a MitraScore ≥4 was no independent predictor of mortality in aFMR indicating a better tolerance toward residual MR. Conclusions: Residual MR is an independent predictor of 1-year mortality in vFMR patients, whereas in aFMR patients, a MitraScore of ≥4 is associated with higher mortality but is not an independent predictor in multivariate analysis. Therefore, minimizing MR through mitral TEER is crucial for survival in vFMR patients, while aFMR patients tolerate significant residual MR better 1 year after the procedure.